Flexible PEDOT:PSS nanopapers as“anion-cation regulation”synergistic interlayers enabling ultra-stable aqueous zinc-iodine batteries

Aqueous zinc-iodine(Zn-I_(2))batteries are promising candidates for low-cost grid-scale energy storage systems.However,the long-term stability and energy density of the Zn-I_(2)batteries are largely hindered by the lack of feasible and scalable methods that coherently suppress polyiodide shuttling and Zn dendrites growth,especially at high current densities.Herein,a flexible,thin and lightweight poly(3,4-ethy lenedioxythiophene):polystyrene sulfonate(PEDOT:PSS)nanopaper is designed as an“anion-cation regulation”synergistic interlayer to tackle the above issues.The PEDOT:PSS interlayer exhibits a 3D nanofibrous network with uniformly distributed mesopores,abundant polar groups and intrinsic conductivity,which renders an even Zn^(2+)flux at Zn anode and facilitates homogeneous current distributions at I_(2)cathode.Meanwhile,such interlayer can act as physiochemical shield to enhance the utilization of I_(2)cathode via the coulombic repulsion and chemical adsorption effect against polyiodide shuttling.Thus,long-term dendrite-free Zn plating/stripping is achieved at simultaneous high current density and high areal capacity(550 h at 10 m A cm^(-2)/5 m Ah cm^(-2)).Zn-I_(2)batteries harvest a high capacity(230 m Ah g^(-1)at 0.1 A g^(-1))and an ultralong lifespan(>20000 cycles)even at 10 A g^(-1).This work demonstrates the potential use of the multifunctional interlayers for Zn-I_(2)battery configuration innovation by synergistic regulation of cations and anions at the electrodes/electrolyte interface.

∼2.5 nm pores in carbon-based cathode promise better zinc-iodine batteries

The relationship mechanism between the material pore structures and cathodic iodine chemistry plays a vital role in efficient Zn-I_(2) batteries,but is unclear,retarding further advances.This work innovatively indicates a great contribution of∼2.5nm pore structure of nanocarbons to efficient iodine adsorption,rapid I^(−)↔I_(2) conversion,and polyiodide inhibition,via scrupulously designing catalysts with controllable pore sizes systematically.The I_(2)-loading within the designed nitrogen-doped nanocarbons can reach up to as high as 60.8 wt%.The batteries based on the cathode deliver impressive performances with a large capacity of 178.8 mAh/g and long-term cycling stability more than 4000 h at 5.0 C.Notably,these is no polyiodide such as I_(3)−and I_(5)−detected during the charge-discharge processes from comprehensive electrochemical cyclic voltammetry,X-ray photoelectron spectroscopy,and Raman technique.This work provides a novel knowledge-guided concept for rational pore design,promising better Zn-I_(2) batteries,which is also hoped to benefit other advanced energy technologies,such as Li-S,Li-ion,and Al-I_(2) batteries.

Enhancing performance and longevity of solid-state zinc-iodine batteries with fluorine-rich solid electrolyte interphase

Rechargeable zinc-iodine(ZnI_(2))batteries have gained popularity within the realm of aqueous batteries due to their inherent advantages,including natural abundance,intrinsic safety,and high theoretical capacity.However,challenges persist in their practical applications,notably battery swelling and vulnerability in aqueous electrolytes,primarily linked to the hydrogen evolution reaction and zinc dendrite growth.To address these challenges,this study presents an innovative approach by designing a solid-state ZnI_(2)battery featuring a solid perfluoropolyether based polymer electrolyte.The results demonstrate the formation of a solid electrolyte interphase layer on zinc,promoting horizontal zinc growth,mitigating dendrite penetration,and enhancing battery cycle life.Moreover,the solid electrolyte hinders the iodine ion shuttle effect,reducing zinc foil corrosion.Symmetric batteries employing this electrolyte demonstrate excellent cycle performance,maintaining stability for approximately 5000 h at room temperature,while solid-state ZnI_(2)batteries exhibit over 7000 cycles with a capacity retention exceeding 72.2%.This work offers a promising pathway to achieving reliable energy storage in solid-state ZnI_(2)batteries and introduces innovative concepts for flexible and wearable zinc batteries.

The dispersion of iron nitride among porous carbon fibers to enhance redox conversion for high-performance zinc-iodine batteries

To address the insulating nature and the shuttle effect of iodide species that would deteriorate the battery performance,herein iron nitride is well-dispersed into porous carbon fibers with good flexibility via the facile electrospinning method and subsequent pyrolysis.The polyacrylonitrile precursor introduces the nitrogen doping under thermal treatment while the addition of iron acetylacetonate leads to the insitu formation of iron nitride among the carbon matrix.The crucial pyrolysis procedure is adjustable to determine the hierarchical porous structure and final composition of the novel carbon fiber composites.As the self-supporting electrode for loading iodine,the zinc-iodine battery exhibits a large specific capacity of 214 mAh/g and good cycling stability over 1600 h.In the combination of in-situ/ex-situ experimental measurements with the theoretical analysis,the in-depth understanding of intrinsic interaction between composited support and iodine species elucidates the essential mechanism to promote the redox kinetics of iodine via the anchoring effect and electrocatalytic conversion,thus improving cycling life and rate performance.Such fundamental principles on the basic redox conversion of iodine species would evoke the rational design of advanced iodine-based electrodes for improving battery performance.

Shapeable carbon fiber networks with hierarchical porous structure for high-performance Zn–I;batteries

Aqueous rechargeable zinc-iodine batteries(ZIBs)emerging as a promising energy storage alternative have attracted considerable attention.However,ZIBs still suffer from the severe shuttle effect of polyiodide and poor reversibility,leading to the poor cycling lifetime and potential safety issues.Herein,the assembly of Al-based metal-organic frameworks(Al-MOFs)in the presence of polyacrylonitrile(PAN)via electrospinning technique enables the formation of Al-MOF/PAN fibers.With the subsequent pyrolysis,the hierarchical porous carbon fibers with nitrogen doping(NPCNFs)are prepared for loading iodine.Benefiting from the confinement effect of the highly porous carbon network and the nitrogen doping,the self-supported carbon nanofiber electrode is capable of inhibiting the shuttle effect of polyiodide species.Especially,the in-situ Raman spectroscopy reveals the reversible two-step conversion reaction between iodine and polyiodide,which enables the best cycling stability for over 6,000 cycles with negligible capacity.This work demonstrates an efficient approach to regulating the porous structure and surface properties in the design of advanced iodine electrodes for high-performance ZIBs.